Gamma-ray Burst 230723A

(All information courtesy of the instrument teams.)

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Results of Observations

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sun 23 Jul 23 04:39:13 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      44
TRIGGER_NUM:     711779928
GRB_RA:           16.983d {+01h 07m 56s} (J2000),
                  17.209d {+01h 08m 50s} (current),
                  16.503d {+01h 06m 01s} (1950)
GRB_DEC:         -63.217d {-63d 13' 00"} (J2000),
                 -63.091d {-63d 05' 28"} (current),
                 -63.483d {-63d 28' 59"} (1950)
GRB_ERROR:       9.77 [deg radius, statistical plus systematic]
GRB_INTEN:       485 [cnts/sec]
DATA_SIGNIF:     6.60 [sigma]
INTEG_TIME:      0.512 [sec]
GRB_DATE:        20148 TJD;   204 DOY;   23/07/23
GRB_TIME:        16723.47 SOD {04:38:43.47} UT
GRB_PHI:          96.00 [deg]
GRB_THETA:       155.00 [deg]
DATA_TIME_SCALE: 0.5120 [sec]
HARD_RATIO:      0.13
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      97%  GRB
2nd_MOST_LIKELY:   1%  Distant Particles
DETECTORS:       0,0,1, 0,0,0, 0,0,0, 1,1,0, 0,0,
SUN_POSTN:       122.29d {+08h 09m 11s}  +20.12d {+20d 07' 27"}
SUN_DIST:        114.67 [deg]   Sun_angle= 7.0 [hr] (West of Sun)
MOON_POSTN:      180.43d {+12h 01m 43s}   +2.50d {+02d 29' 46"}
MOON_DIST:       118.15 [deg]
MOON_ILLUM:      24 [%]
GAL_COORDS:      299.79,-53.81 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      331.46,-60.62 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230723194/quicklook/glg_lc_medres34_bn230723194.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 166.32,-18.87 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sun 23 Jul 23 04:39:31 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      58
TRIGGER_NUM:     711779928
GRB_RA:           44.620d {+02h 58m 29s} (J2000),
                  44.632d {+02h 58m 32s} (current),
                  44.601d {+02h 58m 24s} (1950)
GRB_DEC:         -72.430d {-72d 25' 47"} (J2000),
                 -72.337d {-72d 20' 11"} (current),
                 -72.628d {-72d 37' 41"} (1950)
GRB_ERROR:       10.61 [deg radius, statistical only]
DATA_SIGNIF:     6.70 [sigma]
DATA_INTERVAL:   0.512 [sec]
GRB_DATE:        20148 TJD;   204 DOY;   23/07/23
GRB_TIME:        16723.47 SOD {04:38:43.47} UT
GRB_PHI:          83.00 [deg]
GRB_THETA:       143.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4173 (Gnd S/W Version number)
SUN_POSTN:       122.29d {+08h 09m 11s}  +20.12d {+20d 07' 26"}
SUN_DIST:        105.48 [deg]   Sun_angle= 5.2 [hr] (West of Sun)
MOON_POSTN:      180.43d {+12h 01m 44s}   +2.50d {+02d 29' 42"}
MOON_DIST:       105.00 [deg]
MOON_ILLUM:      24 [%]
GAL_COORDS:      290.68,-41.54 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      319.32,-73.54 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230723194/quicklook/glg_lc_medres34_bn230723194.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_711779928.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        Bright hard burst in the GBM.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The LC_URL file will not be created/available until ~15 min after the trigger.  
COMMENTS:        The POS_MAP_URL file will not be created/available until ~1.5 min after the notice.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sun 23 Jul 23 04:48:02 UT
NOTICE_TYPE:     Fermi-GBM Final Position
RECORD_NUM:      0
TRIGGER_NUM:     711779928
GRB_RA:           20.950d {+01h 23m 48s} (J2000),
                  21.114d {+01h 24m 27s} (current),
                  20.601d {+01h 22m 24s} (1950)
GRB_DEC:         -71.150d {-71d 09' 00"} (J2000),
                 -71.028d {-71d 01' 38"} (current),
                 -71.410d {-71d 24' 36"} (1950)
GRB_ERROR:       4.85 [deg radius, statistical only]
GRB_DATE:        20148 TJD;   204 DOY;   23/07/23
GRB_TIME:        16723.47 SOD {04:38:43.47} UT
GRB_PHI:          94.00 [deg]
GRB_THETA:       147.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       122.30d {+08h 09m 12s}  +20.12d {+20d 07' 22"}
SUN_DIST:        112.62 [deg]   Sun_angle= 6.7 [hr] (West of Sun)
MOON_POSTN:      180.50d {+12h 01m 59s}   +2.46d {+02d 27' 43"}
MOON_DIST:       110.16 [deg]
MOON_ILLUM:      25 [%]
GAL_COORDS:      299.20,-45.74 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      318.13,-66.10 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230723194/quicklook/glg_lc_medres34_bn230723194.gif
LOC_URL:         http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230723194/quicklook/glg_locplot_all_bn230723194.png
COMMENTS:        Fermi-GBM Final Position.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The LC_URL file should be available by the time this FINAL notice is produced.  
COMMENTS:        This notice was generated completely by automated pipeline processing.  
COMMENTS:        Bright hard burst in the GBM.  
COMMENTS:        This is likely a Short GRB.

GCN Circular #34232
The Fermi GBM team reports the detection of a likely SHORT GRB
At 04:38:43 UT on 23 Jul 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230723A (trigger 711779928.466758 / 230723194).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 21.0, Dec = -71.2 (J2000 degrees, equivalent to J2000 01h 23m, -71d 12'), with a statistical uncertainty of 4.8 degrees.
The angle from the Fermi LAT boresight is 147.0 degrees.
The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230723194/quicklook/glg_skymap_all_bn230723194.png
The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230723194/quicklook/glg_healpix_all_bn230723194.fit
The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230723194/quicklook/glg_lc_medres34_bn230723194.gif
GCN Circular #34233
V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, D. Vlasenko, G.Antipov, D.Zimnukhov, V.Senik, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D.Cheryasov, Ya.Kechin (Lomonosov Moscow State University, SAI, Physics Department),
R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA),
R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias),
D. Buckley (South African Astronomical Observatory),
O.A. Gres, N.M. Budnev (Irkutsk State University, API),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
A. Gabovich, V.Yurkov (Blagoveschensk Educational State University)
MASTER-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 230723A ( Fermi GBM team, GCN 34232) errorbox 552 sec after notice time and 586 sec after trigger time at 2023-07-23 04:48:29 UT, with upper limit up to 17.0 mag. The observations began at zenith distance = 57 deg. The sun altitude is -79.1 deg.
The galactic latitude b = -46 deg., longitude l = 299 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2243548
We obtain a following upper limits.
```
Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________

     646 | 2023-07-23 04:48:29 |         MASTER-OAFA | (01h 22m 59.72s , -71d 17m 29.3s) |   C |   120 | 15.9 |        
     801 | 2023-07-23 04:48:29 |         MASTER-OAFA | (01h 22m 59.76s , -71d 17m 29.2s) |   C |   430 | 17.0 |  Coadd 
     795 | 2023-07-23 04:50:48 |         MASTER-OAFA | (01h 22m 53.01s , -71d 18m 28.8s) |   C |   140 | 16.5 |        
     970 | 2023-07-23 04:53:28 |         MASTER-OAFA | (01h 22m 54.39s , -71d 17m 31.5s) |   C |   170 | 16.7 |        
    1165 | 2023-07-23 04:56:38 |         MASTER-OAFA | (01h 23m 00.17s , -71d 18m 30.9s) |   C |   180 | 15.6 |        
```
Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.
GCN Circular #34237
G. Panebianco (Univ. Bologna - INAF/OAS Bologna), C. Casentini (INAF/IAPS), F. Verrecchia, C. Pittori (SSDC, and INAF/OAR), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), A. Ursi (ASI and INAF/IAPS), A. Argan, M. Cardillo, Y. Evangelista, L. Foffano, G. Piano (INAF/IAPS), A. Addis, L. Baroncelli, A. Bulgarelli, A. Ciabattoni, A. Di Piano, V. Fioretti, N. Parmiggiani (INAF/OAS-Bologna), F. Lucarelli (SSDC, and INAF/OAR), M. Marisaldi (INAF/OAS-Bologna, and Bergen University), M. Pilia, A. Trois (INAF/OA-Cagliari), F. Longo (Univ. Trieste and INFN Trieste), I. Donnarumma, E. Menegoni (ASI), A. Giuliani (INAF/IASF-Mi), P. Cattaneo (INFN Pavia), F. Cutrona (Univ. Milano Bicocca) and P. Tempesta (TeleSpazio) report on behalf of the AGILE Team:
The AGILE satellite detected the GRB 230723A at T0 = 2023-07-23 04:38:43 s (UTC), reported by Fermi GBM and Global MASTER-Net (GCNs #34232, #34233).
The burst is clearly visible in the AGILE scientific ratemeters of the MiniCALorimeter (MCAL; 0.4-100 MeV), and AntiCoincidence (AC; 50-200 keV) detectors. The event lasted about 4 s and it released a total number of 3239 counts in the MCAL detector (above a background rate of 499 Hz) and 16051 counts in the AC-Top detector (above a background rate of 2505 Hz).
The AGILE ratemeters light curves can be found at http://www.agilescienceapp.it/notices/GRB230723A_AGILE_RM_ND.png .
The event also triggered a high time resolution MCAL data acquisition, from T0-5.0 s to T0+8.6 s (UTC), and released 1186 counts in the detector, above a background rate of 449 Hz.
The MCAL light curve can be found at http://www.agilescienceapp.it/notices/GRB230723A_084565_617171923.000000.png .
The time-integrated spectrum of the burst between T0 and T0+2s be fitted in the energy range 0.4-10 MeV with a power-law with ph. ind. = -1.8 +/- 0.3, resulting in a reduced chi-squared of 0.94 (48 d.o.f.) and a fluence of 2.5e-06 ergs/cm^2 (90% confidence level), in the same energy range.
At the T0, the event was 103 deg off-axis.
Additional analysis of AGILE data is in progress. Automatic MCAL GRB alert Notices can be found at: https://gcn.gsfc.nasa.gov/agile_mcal.html
GCN Circular #34258
A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin on behalf of the HEND/Mars Odyssey team,
A. Ridnaia, D. Frederiks, D. Svinkin, A. Lysenko, and T. Cline on behalf of the Konus-Wind team,
A. Goldstein, M. S. Briggs, C. Wilson-Hodge, and E. Burns on behalf of the Fermi GBM team,
and
W. Boynton, C. Fellows, K. Harshman, H. Enos, R. Starr, and A.S. Gardner on on behalf of the GRS-Odyssey GRB team, report:
The short-duration GRB 230723A (Fermi GBM detection: The Fermi GBM team, GCN 34232; AGILE/MCAL detection: Panebianco et al., GCN 34237) has been detected by Fermi (GBM), Konus-Wind, AGILE (MCAL, AC), and Mars-Odyssey (HEND), so far, at about 16723 s UT (04:38:43).
We have triangulated it to a preliminary, 3 sigma error box whose coordinates are:
```
 ---------------------------------------------
  RA(2000), deg                 Dec(2000), deg
 ---------------------------------------------
 Center:
   22.909 (01h 31m 38s) -67.059 (-67d 03' 31")
 Corners:
   24.618 (01h 38m 28s) -66.230 (-66d 13' 48")
   24.638 (01h 38m 33s) -66.276 (-66d 16' 34")
   21.066 (01h 24m 16s) -67.859 (-67d 51' 31")
   21.054 (01h 24m 13s) -67.813 (-67d 48' 46")
 ---------------------------------------------
```
The error box area is 265 sq. arcmin, and its maximum dimension is 2.1 deg (the minimum one is 2 arcmin). The Sun distance was 111 deg.
The IPN localization is consistent with, but reduces the area of, the Fermi-GBM final localization (GCN 34232).
This localization may be improved.
A triangulation map and HEALPix FITS file are posted at http://www.ioffe.ru/LEA/GRBs/GRB230723_T16725/IPN/
The Konus-Wind time history and spectrum will be given in a forthcoming GCN Circular.
GCN Circular #34269
A.Ridnaia, D. Frederiks, A.Lysenko, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report:
The short-duration GRB 230723A (Fermi GBM detection: The Fermi GBM team, GCN 34232; AGILE/MCAL detection: Panebianco et al., GCN 34237; IPN triangulation: Kozyrev et al., GCN 34258) triggered Konus-Wind at T0=16725.802 s UT (04:38:45.802).
The burst light curve shows a multipeaked structure, which starts at T0-0.346 s and has a total duration of ~0.62 s.
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB230723_T16725/
As observed by Konus-Wind, the burst had a fluence of 1.66(-0.06,+0.54)x10^-6 erg/cm2, and a 16-ms peak flux, measured from T0-0.220 s, of 8.56(-1.76,+3.29)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range).
Since the main fraction of the burst emission was detected before the trigger, the spectral analysis was performed using the KW 3-channel light curve data.
Modelling the KW 3-channel time-integrated spectrum (measured from T0-0.346 s to T0+0.620 s) by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep), yields alpha = -0.21(-0.26,+0.27) and Ep = 659(-99,+162) keV.
All the quoted errors are at the 68% confidence level. All the quoted values are preliminary.
GCN Circular #34301
S. Guns (UC Berkeley), A. Foster (CWRU), C. Tandoi (UIUC), K. Phadke (UIUC), N. Whitehorn (MSU), G. Holder (UIUC), J. Vieira (UIUC) on behalf of the South Pole Telescope Collaboration:
On 26 July 2023 at 16:48 UTC the South Pole Telescope detected a millimeter-band transient candidate at RA = 43.5275, Dec = -70.4770 (J2000 degrees, uncertainty 12 arcseconds) using the SPT-3G camera in 2 bands centered at 95 GHz and 150 GHz. Peak emission was observed two hours later at 19:14 UTC with flux levels of 18.5 mJy in both bands, after which the SPT slewed away from the observing field. The next series of observations on 28 July showed flux levels consistent with zero. The spatial location of the emission is consistent (1.5 sigma) with GRB 230723A which was detected by Fermi-GBM on 23 July 2023 at RA = 21.0, Dec = -71.2 (J2000 degrees, uncertainty 4.8 degrees). From the SPT-3G transients program, short duration (<1 week) millimeter-band transients that are not associated with nearby stars are rare (<3 events per year). A table of SPT-3G observations is given below.
The lightcurve can be found at: https://pole.uchicago.edu/public/data/transients/lightcurves/SPT-SVJ025406.5-702837.png
```
Observation time  | Flux (95 GHz) | Error (95 GHz) | Flux (150 GHz) | Error (150 GHz)
2023-7-22 05:04 UTC | -3.0 mJy | 2.5 mJy | -3.3 mJy | 3.0 mJy 
2023-7-26 16:48 UTC | 13.3 mJy | 4.4 mJy | 14.0 mJy | 4.9 mJy
2023-7-26 19:14 UTC | 18.5 mJy | 4.4 mJy | 18.5 mJy | 4.9 mJy
2023-7-28 08:12 UTC | 1.7 mJy | 2.5 mJy | 1.8 mJy | 2.8 mJy 
```
The South Pole Telescope is a 10-meter telescope located at Amundsen-Scott South Pole Station and supported by the National Science Foundation and the US Dept. of Energy. The SPT online transient program providing data in this circular is supported by NSF grants AST-1716965 and OPP 1852617, and observes 1500 square degrees of the southern sky at 95, 150, and 220 GHz with an average revisit cadence of 12 hours. For more details on the SPT transient program and survey strategy, please see https://arxiv.org/abs/2103.06166.
GCN Circular #34309
S. Guns (UC Berkeley) on behalf of the South Pole Telescope Collaboration:
In light of the updated error box provided by IPN, the millimeter-band transient event reported by the South Pole Telescope in GCN #34301 is no longer spatially consistent with GRB 230723A (Fermi GBM, GCN #34232; IPN, GCN #34258). The event remains an unexplained, short-duration millimeter-band transient not obviously associated with any known galactic source.

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Jochen Greiner, last update: 01-Aug-2023 [Disclaimer]